1. Field
The present disclosure relates generally to electric motor systems and, in particular, to controlling electric motor systems. Still more particularly, the present disclosure relates to a method and apparatus for controlling the switching frequency at which the motor controller supplies current to an electric motor.
2. Background
An electric motor is a device that converts electrical power into mechanical power. Electric motors are used for various applications. These applications include fans, pumps, tools, disk drives, drills, and other types of devices that may be found in these and other types of platforms.
An electric brushless motor is a commonly used type of electric motor. With electric brushless motors, a controller is configured to change the current in windings in the electric motor. In particular, the current is switched at a frequency that changes the amplitude of the current applied to the windings in phases in a manner that causes the motor to turn. The switching of the current is performed using switches in the form of transistors.
With respect to the performance and durability of brushless electric motors, heat is a limitation. Heat may weaken magnets, cause undesired inconsistencies in the installation of the windings, and other undesirable effects. Further, the operating environment also may expose the electric motor to more heat than desired.
As a result, the electric motor may have a lower than desired lifespan. Additionally, the electric motor may not perform as desired. This situation may result in maintenance, replacement, or both that may occur sooner or more often than desired.
Additionally, the heat generated by the electric motor also may have undesirable effects on other devices that may be in the vicinity of the electric motor. For example, the heat generated by the electric motor may cause these other devices not to perform as desired.
Currently, heat generated by electric motors may be managed through cooling systems. The cooling systems may include fans, liquid cooling devices, and other suitable systems that may dissipate heat from the electric motor.
The use of the cooling system, however, increases the expense of the electric motor. Further, the cooling system also uses space and increases the weight of an electric motor system. Further, use of active cooling systems may reduce the efficiency of the electric motor system. Additionally, in some cases, the amount of space available for the increase in weight may make the use of a cooling system undesirable or impossible.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.